This invention relates to systems and processes for cleaning, chemical sterilizing or disinfecting medical devices. More specifically, this invention relates to method and apparatus for flowing fluid through the interior of lumen device during the process of cleaning, sterilizing, or disinfecting.
Medical instruments have traditionally been sterilized or disinfected using either heat such as is provided by steam, or a chemical in liquid, gas, or vapor state. Prior to sterilization or disinfection, the instruments to be treated are usually first cleaned and then sterilized or disinfected. After sterilization or disinfection with a liquid chemical germicide, purified water is used to rinse the instruments and then the instruments are dried. Numerous publications regarding the cleaning of medical devices and the sterilizing of medical devices are available.
U.S. Pat. No. 5,443,801 discloses a transportable cleaning/sterilizing apparatus and method for inside-outside washing and sterilization of medical/dental instruments. The apparatus functions in four sequential cycles: wash, rinse, sterilize, and dry. The sterilization step is conducted using ozonated and purified water, and the drying step is accomplished by injecting ozonated/deozonated sterile warm dry oxygen, or sterile inert gas into and exhausted from the wash chamber under a positive pressure relative to atmospheric. In this process, the device has to be rinsed with purified water after it is sterilized to remove sterilant residue before drying step.
U.S. Pat. No. 5,505,218 to Steinhauser et al. discloses a device for cleaning, disinfecting and maintaining medical or dental instruments. The device has a pot-shaped container with a multiplicity of mountings in the interior of the container each for one of tool holder, a water supply system, a compressed air supply system, and an ultrasonic transducer. The disinfection is conducted with heated water, and the drying is conducted with hot compressed air. This system is not designed for sterilization.
U.S. Pat. No. 5,279,799 to Moser et al. discloses apparatus for cleaning and testing endoscopes by injecting pressurized air into the sheath and pressurized air and washing liquid into the ducts. A washing chamber is provided which contains retractable cages to hold the endoscopes during cleaning and testing. This process includes washing, disinfecting, final rinsing with purified water, and air drying the ducts of a tubular article. A number of filters are involved in this system, and this system is not designed for sterilization.
U.S. Pat. No. 4,744,951 to Cummings et al. discloses a two-chambered system which provides hydrogen peroxide in vapor form for use in sterilization processes. The sterilant is initially vaporized in one chamber and then applied to the object to be sanitized in another single sterilizing chamber, thereby producing a concentrated hydrogen peroxide vapor which is relatively more effective. The sterilization processes are designed for furnishing concentrated hydrogen peroxide vapor to interior surfaces of articles having a tortuous or a narrow path. However, the sterilization processes are ineffective at rapidly sterilizing lumened devices, since they depend on the diffusion of the hydrogen peroxide vapor into the lumen to effect sterilization.
U.S. Pat. No. 4,863,688 to Schmidt et al. discloses a sterilization system consisting of a liquid hydrogen peroxide vaporization chamber and an enclosure for sterilization. The enclosure additionally may hold containers wherein the hydrogen peroxide sterilant vapor does not contact the interior of the containers. This system is designed for controlling the exposure to the hydrogen peroxide vapor. The system is not designed for sterilizing a lumen device.
U.S. Pat. No. 4,943,414, entitled xe2x80x9cMethod for Vapor Sterilization of Articles Having Lumens,xe2x80x9d and issued to Jacobs et al., discloses a process in which a vessel containing a small amount of a vaporizable liquid sterilant solution is attached to a lumen, and the sterilant vaporizes and flows directly into the lumen of the article as the pressure is reduced during the sterilization cycle. This system has the advantage that the water and hydrogen peroxide vapor are pulled through the lumen by the pressure differential that exists, increasing the sterilization rate for lumens, but it has the disadvantage that the vessel needs to be attached to each lumen to be sterilized.
U.S. Pat. Nos. 4,937,046, 5,118,471 and 5,227,132 to Anderson et al. each disclose a sterilization system which uses ethylene oxide gas for sanitation purposes. The gas is initially in a small first enclosure and thereafter slowly permeates into a second enclosure where the objects to be sterilized are located. A medium is then introduced into the second enclosure to flush out the sterilizing gas into a third enclosure containing the second enclosure. An exhaust system then exhausts the sterilant gas and air from the third enclosure. These systems also have the disadvantage of relying on the diffusion of the sterilant vapor to effect sterilization and hence are not suitable for rapidly sterilizing lumened devices.
U.S. Pat. No. 5,122,344 to Schmoegner discloses a chemical sterilizer system for sterilizing items by vaporizing a liquid chemical sterilant in a sterilizing chamber. Pre-evacuation of the sterilizer chamber enhances the sterilizing activity. Sterilant is injected into the sterilizer chamber from a second prefilled shot chamber. This system also relies upon diffusion of sterilant vapor to effect sterilization and is also not suitable for rapidly sterilizing lumened devices.
U.S. Pat. No. 5,266,275 to Faddis discloses a sterilization system for disinfecting instruments. The sterilization system contains a primary sterilization chamber and a secondary safety chamber. The secondary safety chamber provides for sensing and venting to a destruction chamber any sterilization agent that is released from the primary sterilization chamber. This system, as in other systems, also relies upon diffusion of sterilant vapor to effect sterilization and is also not suitable for rapidly sterilizing lumened devices.
In U.S. Pat. No. 5,492,672 and 5,556,607 to Childers et al, there is disclosed a process and apparatus respectively for sterilizing narrow lumens. This process and apparatus uses a multicomponent sterilant vapor and requires successive alternating periods of flow of sterilant vapor and discontinuance of such flow. A complex apparatus is used to accomplish the method. Additionally, the process and apparatus of ""672 and ""607 require maintaining the pressure in the sterilization chamber at a predetermined subatmospheric pressure.
In U.S. Pat. No. 5,527,508 to Childers et al., a method of enhancing the penetration of low vapor pressure chemical vapor sterilants into the apertures and openings of complex objects is disclosed. The method repeatedly introduces air or an inert gas into the closed sterilization chamber in an amount effective to raise the pressure to a subatmospheric pressure to drive the diffused sterilant vapor further into the article to achieve sterilization. The ""508, ""672 and ""607 Childers inventions are similar in that all three require repeated pulsations of sterilant vapor flow and maintenance of the sterilization chamber pressure at a predetermined subatmospheric pressure.
U.S. Pat. No. 5,443,801 to Langford teaches a transportable cleaning/sterilizing apparatus and a method for inside-outside sterilization of medical/dental instruments. The apparatus avoids the use of heat, pressure, severe agitation, or corrosive chemicals which might damage delicate equipment. This invention uses ozone gas or solution as sterilant. It does not involve the use of sterilant vapor or vaporizing a sterilant solution into vapor, and is not suitable for operations under vacuum because flexible bags or containers are used. Langford""s U.S. Pat. No. 5,711,921 teaches a container with a partition which divides the container into two chambers with a lumen device placed across the partition, one end of the lumen being located in one chamber and the other end in the opposite chamber. By altematingly pressurizing first one and then the other chamber fluid is caused to surge back and forth through the lumen.
Having a single partition creates an opportunity for leakage of fluid past the partition where it contacts the device rather than through the lumen, thereby reducing the amount of fluid flowing through the lumen to effect cleaning, disinfecting or sterilizing of the device.
The present invention provides a method of cleaning, disinfecting or sterilizing a device having a lumen. The method provides a container with at least two interfaces, wherein each interface has a holder for holding the device, and the at least two interfaces divide the container into at least a first compartment, a second compartment, and a third compartment, wherein the first compartment is adjacent to the second compartment. The device is placed into the container across the at least two interfaces, through the holders, wherein the device lumen has a first opening positioned in the first compartment and a second opening positioned in the third compartment. A fluid for cleaning disinfecting or sterilizing is introduced into the first compartment. At least two pressures are created in the container such that the pressure in the first compartment is higher than the pressure in the third compartment, and the pressure in the second compartment is higher than the pressure in the third compartment. The fluid is flowed through the device from the first opening to the second opening.
Preferably, fluid is also introduced into the second compartment. The fluid can be a liquid, a mist, an aerosol or a mixture of gas and liquid. To prevent portions of the device from being occluded by the holders, one or both of the holders can be opened during a portion of the process while the fluid is in the first, second and third compartments. Preferably, the pressures in said the first compartment, the second compartment, or the third compartment are monitored, and preferably controlled such that the pressure in the second compartment is equivalent to or higher than the pressure in the first compartment. More preferably, the pressure in the second compartment is higher than the pressure in the first compartment. Rather than increasing the pressure in the first chamber, the pressure in the third chamber can be reduced. To enhance especially the disinfection and sterilization, the fluid in the lumen device or in the container may be vaporized during the process.
An apparatus according to the invention flows a fluid through a device having a lumen with first and second openings into said lumen. The apparatus comprises a container with at least a first compartment connected with a first port, a second compartment connected with a second port, and a third compartment connected with a third port, wherein the first compartment is adjacent to the second compartment. A first interface separates the first and second compartments and a second interface separates the second and third compartments. Each of the first and second interfaces has a holder for holding the lumen device, with the holders adapted to hold the device with the first opening into the lumen in the first compartment and the second opening into the lumen in the third compartment. A source creates a positive pressure difference between the first compartment and the third compartment and a positive pressure difference between the second compartment and the third compartment.
Preferably, a source of fluid connects to the first port or the second port. The fluid can be a liquid, a gas, a mist, an aerosol or a mixture of gas with liquid. Preferably, at least one of the holders has a controllable opening, and more preferably each holder has a controllable opening. Pressure indicators can indicate the pressure in one or more of the first, second, and third compartments and pressure controllers can control the pressure in in one or more of the first, second, and third compartments. A pump to can be provided to evacuate the container.